Boss Sibelon are the harder version of the original Sibelon and are found in the Lower Maps. They normally require a lot of patience to kill, as they have a lot of health and are difficult to bring down in a non Full-Elite ship. It is recommended that you get a number of outfit members to assist you, as you can easily be killed while fighting one - either by the Alien, an enemy player, or a notorious Company Killer. After you finish killing it, you and your outfit members (if you are going solo you get it all) will get a good reward along with the large cargo drop.